1. Field of the Invention
The present invention relates to a brine type air conditioning apparatus in which a brine cooled by a brine-refrigerant heat exchanger circulates into a cooler in a passenger compartment to cool the passenger compartment. The present invention is preferably employed for a vehicle.
2. Description of Related Art
Recently, in view of preventing warmth of the earth, there has been proposed an air conditioning apparatus for a vehicle, in which refrigerant in a refrigeration cycle is changed from feron to flammable gas such as propane gas to cool a passenger compartment of the vehicle, as disclosed in JP-U-58-54904.
In the above-described air conditioning apparatus for a vehicle, a cooler (evaporator) for cooling conditioned air by latent heat of evaporation of the flammable gas is disposed in a passenger compartment; and therefore, the flammable gas may be leaked into the passenger compartment as a closed space from a pipe connecting portion of the cooler, or the like.
To prevent the gas from leaking into the passenger compartment, the inventors of the present invention have developed a brine type air conditioning apparatus in which a brine-refrigerant heat exchanger is disposed in an engine compartment (a space opened to the atmosphere) outside the passenger compartment, brine (water to which a compound for decreasing a freezing temperature is added) is temporarily cooled in the brine-refrigerant heat exchanger, and this low-temperature brine circulates into a cooler disposed in the passenger compartment to cool the passenger compartment.
In the brine type air conditioning apparatus, the inventors have examined, as a temperature control system for controlling a temperature of air blown into the passenger compartment, a system for adjusting a heating amount in a heater using hot water (engine cooling water) usually employed in a vehicle, e.g., an air-mixing type for adjusting a ratio of an amount of cool air and an amount of warm air.
According to this temperature control system, after the conditioned air is cooled and dehumidified by the low-temperature brine, a temperature of which is lowered down to approximately 0.degree. C., the cooled air is re-heated up to a desired temperature; and therefore, it is preferable in view of the air-conditioning function. However, as the refrigeration cycle, since the brine is always cooled down to approximately 0.degree. C., when the re-heating amount in the heater becomes large as in the intermediate seasons of spring and fall, the consumed energy in the refrigeration cycle may be increased wastefully.